1. Field of the Invention
The present invention relates to a portable telephone with a liquid crystal display and, more particularly, to a portable telephone capable of reducing power consumed by the lighting of a backlight or illumination light,
2. Description of the Prior Art
In a conventional portable telephone, the backlight or illumination light (to be referred to simply as a backlight hereinafter) is lit up for a predetermined period of time only when the user presses any key. When the user wants to use the portable telephone in a dark place at night, the display portion of the portable telephone cannot be seen due to the ambient darkness. To use it, the user must press any key, resulting in inconvenience.
To solve this problem, a portable telephone with a fold down mechanism has been proposed, as described in Japanese Unexamined Patent Publication No. 7-74691. According to the characteristic feature of this telephone, it has an LED for illuminating dial keys and serving as the backlight of an LCD (Liquid Crystal Display), a photosensor for detecting the ambient brightness, and a use state detection means for detecting a use state upon detecting that a dial key was pressed within a predetermined period of time. The LED is turned on in accordance with the detection of the use state and ambient darkness. The battery power can be saved without using a mechanical switch or sensor, or sacrificing durability in detecting the open/closed state of the fold down mechanism.
Another conventional portable telephone is described in Japanese Unexamined Patent Publication No. 9-27844 as a portable telephone with a display function. The lighting time of a backlight for illuminating a liquid crystal display is minimized to save the power consumption, thereby maximizing the telephone use time without overcharging. The lighting time of the backlight is controlled in a dark place as follows. According to the characteristic feature of this telephone, for example, in a dark place, the backlight is turned on in response to the input of a speech communication start key or termination at the start of speech communication. A timer is then started, and the backlight is turned off until a speech input is detected or with a lapse of a predetermined period of time.
In the prior arts described above, a C-MOS one-chip system IC or liquid crystal display is used or employed to reduce the power consumption of the batteries of the portable telephones to allow long-time use of the batteries. In particular, a variety of techniques have been developed to reduce the power consumption of the backlight for the liquid crystal display. The reduction in power consumption must be considered together with convenience in use of a portable telephone in many respects.
The present invention has been made in consideration of the above situation, and has as its object to provide a portable telephone which can be immediately operated even in a dark place to improve operability and can reduce power consumption of a battery to allow longer-time use.
In order to achieve the above object according to the first main aspect of the present invention, there is provided a portable telephone having a liquid crystal display with a backlight, comprising a touch sensor arranged on a side surface of a main body and an operation unit for inputting a telephone number or the like, wherein the telephone has two preset modes, a touch mode for the touch sensor and a key operation mode for the operation unit, and the backlight is lit when a user sets one of the two modes.
According to the second main aspect of the present invention, there is provided a portable telephone having a liquid crystal display with a backlight, comprising a touch sensor arranged on a side surface of a main body, a photosensor for detecting an ambient lightness, an operation detector for detecting an operation of an operation unit for inputting a telephone number or the like, and a sound sensor for detecting a speech input, wherein the telephone has two modes, a first mode of lighting the backlight upon detecting signals from the touch sensor, photosensor, and sound sensor, and a second mode of lighting the backlight upon detecting signals from the operation detector, photosensor, and sound sensor.
In the portable telephone of the first or second main aspect, lighting the backlight by the touch sensor is controlled.
According to the present invention, the operation of the portable telephone according to the first and second main aspects requires the first step of determining whether a sensor signal from a touch sensor is detected, the second step of determining upon detecting the sensor signal whether a backlight lighting flag is ON, the third step of, when the sensor signal is not detected, returning to the first step of determining whether the sensor signal from the touch sensor is detected, the fourth step of lighting the backlight when the backlight lighting flag is ON, the fifth step of, when the backlight lighting flag is OFF, returning to the first step of determining whether the sensor signal from the touch sensor is detected, and the sixth step of returning to the first step of determining whether the sensor signal from the touch sensor is detected after the fourth step of lighting the backlight.
As can be apparent from the above aspects and related explanation, in the portable telephone of the present invention, when the user sets the backlight lighting flag ON in advance so as to light the backlight upon touching the touch sensor by a key operation or the like, the backlight can be lit to see the display portion by simply holding the portable telephone with a hand without performing any key operation even if the display portion of the portable telephone cannot be seen in a dark place.
When the backlight lighting flag is OFF, the backlight is lit with any key-in operation on the operation unit 14. In this case, the lighting time can be shortened as compared with the lighting of the backlight upon touching the touch sensor.
The above and many other objects, features and advantages of the present invention will become manifest to those skilled in the art upon making reference to the following detailed description and accompanying drawings in which preferred embodiments incorporating the principle of the present invention are shown by way of illustrative examples.